catch_break governs whether interactive interrupt (ctrl-C)
terminates the program or raises the Break exception.
Call catch_break true to enable raising Break,
and catch_break false to let the system
terminate the program on user interrupt.

valocaml_version : string

ocaml_version is the version of Objective Caml.
It is a string of the form "major.minor[additional-info]"
Where major and minor are integers, and additional-info is
a string that is empty or starts with a '+'.